Technics SB-F1 blown speaker repair

Status
Not open for further replies.
So I was temporarily using my little SB-F1 speakers as monitors to do some mess about recording and I think I blew one of the drivers 🙁
I was recording bass guitar and monitoring the PC audio through these via a HiFi amp at not particularly loud volume and they started making a wierd noise. I hooked them up to another amp to check it wasn't the amp but its defiantly the speaker. Sounds like this:
YouTube

I took the driver out and inspected it and there is no obvious fractures in the cone or the edge/ring (terminology?)

On the speaker test video the higher frequencies seem ok so its not the tweeter....

I have 2 pairs of these because I like them so much in case anyone was wondering why there is a silver one in the video also. I also have a pair of F2's! The F1's are amazing little speakers. Id be gutted if it cant be repaired.

Any help would be appreciated as always.

🙂
 
Update......

I put the speaker and tweeter assembly from a known 'good' speaker with the speaker I thought was blown. The problem was still there. So the drivers in the speakers which I thought Id blown must be ok? So the issue is with the circuity in the broken speaker, not the drivers?

Can anyone advise?
 
Well, after re capping these and replacing the resistors, the problem wansnt solved.
I re checked everything, re tested the speakers with the board and rear casing of a known good speaker and they worked as normal. I thought it must be the x overs and had reassembled the bad speaker and had given up when I noticed a little plastic disc on the inner base of the 'known good' speaker. It is glued over a screw hole in the dead centre of the speaker casing. I had seen the disc loose in the bad speaker but assumed it was to go over the top of the cap on the circuit board for some reason, as it was the same diameter! The screw holes in the speaker cases could be used to mount these speakers on little tripods and the disc keeps the enclosure air tight! I hooked the bad speaker back up to am amp and tried the speaker test sounds again. The weird sound which was caused by low frequencies went away as soon as I put my finger over this hole. There was quite a bit of pressure coming from there!

I used very strong duct tape to seal the hole from the inside, taping over the disc on the good speaker as well to prevent it happening in the future.
 
Status
Not open for further replies.